Dam Removal: When Less is More (Thurs Oct 26th 4:15-4:45pm)

August 17, 2017

Laura Wildman
Dam removals come in all shapes and sizes, with a myriad of different issues that impact the final design, sediment management, and channel restoration approaches selected. Some projects require a more “engineered” design when critical infrastructure is at risk; however, many dam removal projects can be designed with a “less is more” approach, letting the river do the work, and setting the river back on a trajectory to restore itself. We will discuss multiple successful dam removal projects that we purposefully designed to avoid “heavy handed” approaches. For these projects, an upfront understanding of the channel’s equilibrium slope, history of sediment deposition, and understanding of potential risks and impacts were critical to the final design choices made. Habitat building blocks were added as needed, however grade controls, hard armoring, extensive plantings, and active channel reestablishment were avoided. The upstream channels were allowed to remain dynamic and re-establish themselves. Examples of completed projects such as the Tannery Dam removal in New Hampshire and the Pleasant Grove mitigation site and dam removal in New Jersey will be described as well as other dam removals throughout the greater northeast. While a “less is more” approach is not always attainable, we will discuss the benefits of this approach, such as ease of constructability, and how to look for the right opportunities to apply this approach.